The tiny silhouettes seen from the base are unmistakable. Small dots, moving slowly up Uluru's steep gradient, hanging to chains bolted into sandstone. Alice, a senior Anangu woman, says they refer to climbers as Minga – ants in the Pitjantjatjara language. “They blindly follow one path up and one path back.”

Climbing Uluru has long caused deep cultural offence. It has scarred and eroded the sacred site and may well be causing significant environmental damage.

In 2010, the Uluru Kata-Tjuta national park board of management – which includes traditional owners from within the region and Parks Australia representatives (traditional owners make the majority of the board) – released an updated management plan (pdf). This included a commitment to close the Uluru climb once the number of climbers dropped below 20% of the total number of park visitors. But Guardian Australia has learned that although the numbers appear to have fallen below that threshold, there is currently no plan in place to close the climb, as the hurdles for closure have been changed again since the plan’s publication.

Chris Martin, manager of visitor and tourism services for the park, said climb counters had been installed on the top of the rock to measure the number of people partaking in the climb. “It’s measuring less than 20% of people visiting the park,” he said. That evidence is reinforced by two surveys of 636 people in total, undertaken by Parks Australia in 2012, which indicated around 17% of visitors had climbed or intended to climb.

Around three-quarters of visitors in 1990 climbed, falling to 52% in 1995, and 38% of visitors in 2006. Further research undertaken by Parks Australia over a three-year period concluded that 98% of visitors to the park would not be put off if the climb were closed. Previously the management plan contained three triggers for closing the climb. It explicitly stated that only one of the three requirements needed to be met before climb closure should start. Now it appears that all three, with the other two being the installation of new visitor experiences and ensuring natural and cultural experiences were the key reasons for tourists visiting the park, need to be met before the climb will be closed. The management plan says 18 months’ notice should be given to the tourism industry before closure.

In a statement, Parks Australia said the changes to the management plan had been agreed unanimously by the board of management.

Bob Randall, a respected Anangu elder expressed anger at the continuing delays to closure. “The system that is now is in place is what we call a gammon that they care, but that’s total hypocrisy. Parks [Australia] and other organisations claim that ‘we understand your Tjukurpa’, but, hey, you’re showing nothing but terrible disrespect if you support a system that allows you to climb Uluru.”

Tjukurpa is the knowledge gained from the thousands of years the Anangu have owned the land. It is the spiritual interpretation of the area, the desire to live harmoniously with the natural landscape and is the key to understanding why climbing Uluru is deeply offensive.

“Anangu never climb to the top of Uluru, knowing that Tjukurpa goes all around the base,” said Alice. She etched the story of Langkata, the blue-tongued lizard man, in the burnt red sand. Langkata was the “original disrespectful visitor”. He climbed Uluru and met his just rewards.

Langkata travelled from the west to Uluru and spotted smoke to the south, where Panpanpalala, the Crested Bellbird Man, lay asleep, Alice said. Langkata followed the smoke, and stole the meat of an emu carcass that Panpanpala had roasted. He retreated and hid in a cave near the summit of Uluru. When Panpanpalala awoke, he was furious and followed the tracks to the cave. He set fire to the base and waited. Langkata was smoked out. He fell to his death. It has always been wrong to climb.

In 1985, Prime Minister Bob Hawke handed Uluru back to the Anangu people. The national park was immediately leased back to the parks’ authority for 99 years and placed under joint management. To this day, the Australian Labor party celebrates the handover as a proud moment in the reconciliation process.

Before visitors start to climb Uluru, they are informed of the cultural sensitivities about setting foot on the rock. At the base a sign reads: “Our traditional Law teaches us the proper way to behave. We ask you to respect our Law by not climbing Uluru.” Tour operators are required to inform their guests too. But still they climb.

James Douglas, a tourist from the US on an organised tour, stood at the base of the climb, gazing upwards. He said: “It seems like it would be a great view to see from the top. It looks kind of tough,” he says, resigned to climbing later in the day.

Had he been made aware of the cultural sensitivities around doing it?

“I understand the cultural sensitivity and I would be sensitive to it, but it would be an interesting challenge to get on top,” he said.

But surely it was difficult to be sensitive if you were doing it anyway?

“I wouldn’t be boasting to the original people. I think that’s a big part of it. I wouldn’t be jumping up and down, or being insensitive,” he said.

At present 54% of local tour operators offer the climb to guests, although some do not actively promote it. Research undertaken in 2006 by the Australian National University concluded that Japanese tourists were most likely to climb Uluru, with 83% of Japanese visitors electing to do so. Parks Australia concede they have no quantifiable data on how many wholesalers working with overseas tour companies actively promote the climb.

Kerrie Bennison, natural and cultural resources manager of the park, told Guardian Australia that the climb was also inflicting irreparable environmental damage on the site. “The scar that it leaves, you can see from being here,” she said. “The path is worn and it’s a very obvious impact from having lots of feet up and down it each time.”

Researchers from Newcastle University are also investigating whether bacteria left from human excrement at the top of Uluru, where there is no sanitation provision, is affecting local wildlife populations.

Uluru Kata-Tjuta national park was declared a commonwealth reserve under the Environmental Protection and Biodiversity Conservation Act of 1999. Contained within the act are clauses that require authorities to preserve the area in its natural condition and also to prohibit any damage of heritage.

But Parks Australia says that leaving the climb open is not a direct contravention of the act.

Late in the day, as the last embers of sunlight hung over Uluru, the rock shifted from deep red to purple, casting long shadows on the flatlands around. At the viewing platform small groups of sightseers set up camp, holding a sausage sizzle by the roadside.

Clutching a sausage sandwich in one hand and a spatula in the other, Andrew Cox, 56, from Coffs Harbour in New South Wales, took in the view. It was his sixth time at Uluru. He came first as a 20-year-old, and climbed the rock. But now, following the handing back in 1985, he wouldn’t dream of it. “I think it’s something that is national heritage,” he said, “that we should respect. And certainly the traditional owners wish us not to climb it, and I think their wishes are something we should probably follow.”

Cox returned to his sausages, content with the familiar panorama that stood before him.